Manufacture of cyclopentadienyl-manganese carbonyl compounds



United States 2,915,505 Patented Dec. 8, 1959 thee Hymin Shapiro, Baton Rouge, Lin, assignor to Ethyl Corporation, New York, N.Y., a corporation of Delaware No Drawing. Application November '18, 1957 Serial No. 696,955

6 Claims. (Cl. 266-429) This invention relates to the manufacture of organo metal carbonyl compounds and more particularly to the production of cyclopentadienyl manganese tricarbonyl compounds.

Cyclopentadienyl manganese tricarbonyl compounds have been found to be exceptionally effective antiknocks for use in fuel, for spark plug ignition internal combustion engines. Many of these compounds, principally the liquid compounds, additionally have auxiliary properties which make them entirely practical and desirable for commercial use. These auxiliary properties include high solubility in hydrocarbon fuels, such as gasoline, and thermo-stability either alone or in gasolines. Such stability is necessary for use under the widely varying conditions to which gasoline and other fuels are normally subjected. Possibly of even greater importance, these compounds do not tend to form any appreciable deposits on the engine pistons, valves and spark plug surfaces, and likewise are not abrasive to the engine parts, as are characteristic of iron compounds.

It is accordingly an object of this invention to provide an improved method for manufacture of cyclopentadienyl manganese tricarbonyl compounds. Another object is to provide a process of the above type which gives high conversions to the desired cyclopentadienyl manganese tricarbonyl compounds and which minimizes the formation of undesired by-products. A more specific object is to provide a process which eliminates or materially reduces the production of polymeric by-products which interfere with the recovery of the desired product and which limits the over-all utilization of the starting materials. A specific object is to provide a method of the above type suitable for large scale commercial production of cyclopentadienyl manganese tricarbonyls, particularly alkylcyclopentadienyl manganese tricarbonyls. Other objects and advantages of this invention will be apparent from the following description and appended claims.

These and other objects of the present invention are accomplished if a cyclopentadienyl manganese salt and carbon monoxide are reacted in the presence of a metal hydride or organo-metal compound in which the metal is selected from the group consisting of an alkali metal, alkaline earth metal, or an earth metal i.e. metals of groups IA, IIA or IIIA of the periodic table. By an organo-metal compound is meant a compound having a metal-carbon bond. More specifically, the process of this invention is conducted in the presence of a metal compound of the metals defined above, the metal compounds having the general formula MR,,,, wherein R is a radical selected from the group consisting of hydride, alkyl, alkynyl, alkenyl, aryl and combinations of such radicals including alkaryl and aralkyl radicals. The alkyl radicals can be cycloaliphatic. The subscriot x is a small Whole number, usually equal to the valence of the metal M.

The above process provides considerably greater yields of the desired cyclopentadienyl manganese tricarbonyl compounds than heretofore attained by known methods and at the same time minimizes undesired by-product formation, e.g. by reducing polymer formation. When, for example, a bis(cyclopentadienyl) manganese compound is reacted with carbon monoxide by the known process, only half of the cyclopentadienyl radicals can theroretically form a part of the product, the other cyclopentadienyl radical becomes polymerized and is a major component of the crude reaction product. Moreover, even using the best techniques now known, only from to 40 percent conversion to product of the initial cyclopentadiene is obtained, whereas when the process is conducted in the presence of a MR compound, in accordance with this invention, greater than 50 percent of the initial cyclopentadiene is normally utilized in the formation of the desired cyclopentadienyl manganese tricarbonyl product. In addition to the savings obtained in better utilization of the feed materials, the problem of recovery and purification of the desired product is materially simplified due to elimination or reduction of the by-product polymer.

More particularly the. process of this invention comprises reacting the cyclopentadienyl manganese salt and carbon monoxide under at least a moderate carbon monoxide pressure, using from about 0.1 mole to about 2 moles of the MR, compound per mole of the cyclopentadienyl manganese salt, preferably mole equivalent quantities, at a temperature of from about -50 to about 300 C., or at least below the temperature at which the product tends to decompose at an unsatisfactory rate. The preferred temperature is between about l00250 C. Although the process can be conducted in the absence like.

of a solvent or diluent, a solvent system is normally preferred.

The cyclopentadienyl manganese tricarbonyl compounds, which can be produced in accordance with the process of this invention, can contain any cyclomatic group having the 5 carbon atom ring such as is found in cyclopentadiene itself. This cyclomatic group can be substituted with one or more monovalent hydrocarbon radicals or can be of a condensed ring type, such as the indenyl or fluorenyl type. The process is particularly suitable for the manufacture of compounds in which the cyclomatic group contains from 5-13 carbon atoms. These compounds have a molecular weight up to about 315.

Typical examples of cyclopentadienyl manganese tricarbonyl compounds which can be produced by the process of this invention are cyclopentadienyl manganese tricarbonyl, methylcyclopentadienyl manganese tricarbonyl, n-octyl cyclopentadienyl manganese tricarbonyl, diethyl cyclopentadienyl manganese tricarbonyl, phenyl cyclopentadienyl manganese tricarbonyl, benzyl cyclop-entadienyl manganese tricarbonyl, indenyl manganese tricarbonyl, fluorenyl manganese tricarbonyl and the like.

Illustrative examples of other cyclopentadienyl radicals are 2,4-di-methyl-3-tert-butylcyclopentadienyl; isopropenyl cyclopentadienyl, acetyl cyclopentadienyl and the The cyclopentadiene radical itself can have from 1 to 5 of one or more of the above substituted radicals. Likewise, the indenyl radical can have from 1 to 7 of any one or more of the above radicals and the fluorenyl radical can be substituted by 1 to 9 of the above radicals. Typical examples of indenyl-type radicals are Z-methyl indenyl; 3,4-divinyl indenyl; l-phenyl indenyl; 3-ethyl fluorenyl; 4,5-dipropyl fiuorenyl; 6-vinyl fiuorenyl; 4- benzyl-fluorenyl; Z-m-tolyl fiuorenyl and the like. Other examples of suitable cyclomatic radicals includes 4,5,6,7- tetrahydroindenyl; 1,2,3,4,5,6,7,8-octahydrofiuorenyl; 3- methyl-4,5,6,7-tetrahydroindenyl and the like.

As pointed out above, the MR compounds can be compounds in which M is an alkali metal, alkaline earth metal or an earth metal. The alkali metal can be any of the group IA metals, including sodium, lithium, potassium, rubidium and cesiurn, the preferred metal being sodium from the standpoint of both economics and operation. The alkaline earth metals suitable with this invention are any of the group 11A metals, including beryllium, magnesium, calcium, strontium and barium. The earth metals are metals of group IIIA and include boron, aluminum, gallium, indium and thallium.

Typical examples of suitable MR compounds are sodium hydride, ethylsodium, ethyllithium, ethylpotassium, phenyl sodium, naphthyl sodium, tolyl sodium, xylyl sodium, lithium methyl, lithium phenyl, potassium methyl, potassium octyl, magnesium diethyl, magnesium diphenyl, magnesium dicyclohexyl, calcium methyl, calcium phenyl, strontium ethyl, aluminum trimethyl, aluminum triethyl, aluminum triisobutyl, aluminum hydride, ethyl aluminum dihydride, diethyl aluminum hydride, sodium diethyl-aluminum hydride, lithium aluminum hydride, scandium triethyl and the like. In certain cases it is sometimes advantageous to employ halogen or other anion-containing compounds, such as ethyl magnesium chloride, phenyl magnesium bromide, methyl aluminum dichloride, ethyl aluminum dichloride, diethyl aluminum chloride, ethylaluminum sesquichloride, diethyl aluminum bromide and the like. The organo groups can contain up to about 20 carbon atoms per organo radical.

Any of a wide variety of cyclopentadienyl manganese salts can be employed in the process of this invention although the halides (particularly, the chloride) are preferred. In addition to the halides, i.e. chloride, bromide, iodide, and fluoride, both inorganic and organic anions can be used. The monovalent anions are preferred. Illustrative examples are cyclopentadienyl manganese chloride, methylcyclopentadienyl manganese bromide, n-decylcyclopentadienyl manganese iodide, indenyl manganese fluoride, fluorenyl manganese nitride, cyclopentadienyl manganese nitrate, methylcyclopentadienyl manganese acetate, and cyclopentadienyl manganese naphthenate. Other suitable cyclopentadienyl manganese salts are the butyrate, phenate, phosphide, azide, cyanide, thiocyanate, isopropoxide and the like.

The MR compounds which are in a solid state under reaction conditions should preferably be subdivided prior to reaction. Best results are obtained when the MR compound, if a solid, has a particle size of 5 to 200 microns. The most preferred particle size is from to 50 microns average particle size. A particularly suitable method of preparing solid MR compounds is the use of a grinding operation and particularly a ball mill in which the milling is conducted under a suitable solvent, such as those noted above. In fact, optimum results are obtained if the reaction is conducted while ball milling the entire reaction mass.

A convenient method of preparing the cyclopentadienyl manganese salts is by the reaction of a manganese salt, e.g. a halide, with a bis(cyclopentadienyl) manganese compound. In this preparation, essentially stoichiometric quantities are frequently preferred, although an excess of either the manganese halide or the bis(cyclopentadienyl) manganese can be used, generally from 0.5-2 moles of manganese halide per mole of the bis(cyclopentadienyl) manganese compound.

The bis(cyclopentadienyl) manganese compounds can be produced by several known methods. In general, these compounds are produced by reaction of an alkali metal, e.g. soditun, with the cyclopentadiene hydrocarbon in a suitable solvent system at a temperature of from 0250 C. and thereafter reacting this product with a manganous salt, eg. a halide, at temperatures above about 100, preferably above 130 C. The cyclopentadiene hydrocarbon is usually employed in lmole percent excess, based on the moles of alkali metal. Alkali metal compounds, such as sodium hydride and sodamide, can also be employed in the first step. Hydrocarbons, ethers, amines, and other solvents can be employed in the process. Illustrative examples of solvents are hexane, n-decane, mineral oil, cyclopentadiene dimer, benzene, toluene, naphthalene, diphenyl, diphenyl ether, diethyl ether, ethylene glycol dimethyl ether, liquid ammonia, triethanolarnine and the like. The reaction of the manganous salt with the cyclopentadienyl alkali metal compound normally requires a solvent and, for this purpose, the other types give best results. The ethylene glycol dialkyl ethers are preferred.

Carbon monoxide can be employed over a wide pressure range, e.g.. from 1-1000 atmospheres. A more preferred range is from 10-100 atmospheres. The carbon monoxide purity is not critical but is important. It is best to use carbon monoxide of -100 percent purity.

As pointed out above, solvents can be used in the present process and are frequently preferred. The solvent can be the same as used in the preparation of the bis(cyclopentadienyl) manganese compound above. Typical examples of suitable solvents are hydrocarbons, ethers and amines. Suitable hydrocarbon solvents are the paraffin types, such as n-pentane, isopentane, hexanes, heptanes, n-octane and mineral oils; and aromatic types, such as benzene, toluene, xylene, naphthylene and alkylated naphthylenes, e.g. the methylated naphthylenes, and diphenyl. Illustrative examples of ethers which can be used in this invention are dimethyl ether, methyl ethyl ether, diethyl ether, di-isopropyl ether, diphenyl ether, and dioxane. The most preferred solvents are the ethylene glycol alkyl other types, such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether and diethylene glycol dibutyl ether. Suitable amines useful in carrying out the present invention are dicyclohexylamine, benzylamine, N-methylaniline, N-ethylaniline, N-ethylnaphthylamine, N,N-dimethylaniline, tri-n-hexylamine, N- methyl diphenyl amine. Quantities of solvent from 0.1 part to parts per part of manganese compound can be employed. Preferably rather concentrated solutions are used, eg from about 0.5 part to about 10 parts per part of manganese compound.

The following are typical examples which illustrate the process of the present invention. All quantities in the following examples are given in parts by weight.

EXAMPLE I Methylcyclopentadienyl manganese chloride prepared from 19 parts of bis(methylcyclopentadienyl) manganese and 11.4 parts of manganese chloride in 80 parts of diethylene glycol dimethyl ether was mixed with 4.4 parts of sodium hydride in a pressure reactor equipped with a stirrer and means to feed and vent gases. Upon addition of the sodium hydride to the methylcyclopentadienyl chloride, a vigorous exothermic reaction took place. The reactor was then sealed and the reaction was carried out under carbon monoxide pressure at C. and at C. while agitating the mixture. The pressure drop of 800 p.s.i.g. was observed while operating at a maximum pressure of 500 pounds at 165 C. over a period of 2% hours. An additional 90 pound drop occurred over a period of 2 hours at 195 C. and a maximum carbon monoxide pressure of 600 p.s.i.g. The reaction mixture was discharged from the reactor and any remaining product was washed from the reactor with diethylene glycol dibutyl ether (50 parts). The product was then vacuum distilled to remove the volatile components, including the methylcyclopentadienyl manganese tricarbonyl product. The crude product is fractionated to recover essentially pure methylcyclopentadienyl manganese trioarbonyl as the middle fraction. The product was recovered in 53% conversion based upon the methylcyclopentadienyl manganese chloride reactant.

The product is thereafter further fractionated to obtain a highly pure methylcyclopentadienyl manganese tricarbonyl and this product is then blended with gasoline. The following table shows data with the octane increase of a commercial gasoline having an initial boiling point of 94 F. and a final boiling point of 390 F. The antiknock value of the fuel as determined by the ratings are given in octane numbers for values below 100 and in Army-Navy performance numbers for values above 100. The method of determining performance numbers is explained in the booklet Aviation Fuels and Their Eifect on Engine Performance, NAVAER-06-5-501, USAF TD. No. 06554, published in 1951. For numbers below 100, the Research Method is employed. The Research Method of determining the octane number of a fuel is generally accepted as a method of test which gives a good indication of fuel behavior in full-scale automotive engines under normal driving conditions and the method most used by commercial installations in determining the value of a gasoline or additive. The Research Method of testing antiknocks is conducted in a singlecylinder engine especially designed for this purpose and referred to as the CPR engine. This engine has a variable compression ratio and during the test the temperature of the jacket water is maintained at 212 F. and the inlet air temperature is controlled at 125 F. The engine is operated at a speed of 600 rpm. with a spark advance of 13 before top dead center. The test method employed is more fully described in test procedure D-908-55 contained in 1956 edition of ASTM Manual of Engine Test Methods for rating fuels.

Table C H Mn(CO) g. metal/gal.: Octane rating 83.1 1.0 92.7 2.0 95.8 3.0 98.0

EXAMPLE II Methylcyclopentadienyl manganese chloride solution prepared, as in Example I, from 19 parts bis(methylcyclopentadienyl) manganese and 11 parts manganese chloride in 80 parts of diethylene glycol dimethyl ether was charged to the reactor of Example I. Phenylsodium prepared by reaction of parts of sodium metal with parts chlorobenzene in 2,2,4-trimethylpentane at 80 was then charged to the reactor. The henylsodium was separated from the hydrocarbon solvent by filtration, prior to addition to the reactor. The reactor was sealed and was pressurized to 500 p.s.i.g. with carbon monoxide and was then heated to 165 C. After the reaction temperature was reached, the pressure was allowed to drop to 400 p.s.i.g. after which the carbon monoxide was again added to the reactor, giving a maximum pressure of 500 p.s.i.g. Reaction continued, as in Example I, until carbon monoxide absorption was complete. The total pressure drop was 850 p.s.i.g. This pressure drop was 1.43 times as great as that obtained in a corresponding control experiment wherein no phenylsodium was present and bis(methylcyclopentadienyl) manganese, was used.

EXAMPLE III yl ether prepared as in Example I was added 3.5 parts of triethylaluminum. Carbon monoxide was added to this reaction mixture and the reactor was maintained at a temperature of 160 C. until no further carbon monoxide was taken up by the reaction mixture. The methylcyclopentadienyl manganese tricarbonyl product is recovered according to the procedure of Example I in comparable yields. When vinyl magnesium bromide or allylsodium is substituted for triethylaluminum, similar results are obtained.

EXAMPLE IV Example I was repeated except that 1.7 parts of lithium aluminum hydride was employed instead of the sodium hydride. The same reaction conditions were used as in Example I and similar results were obtained.

EXAMPLE V Example I is repeated except that cyclopentadienyl manganese bromide is reacted with carbon monoxide in the presence of sodium borohydride. The temperature of the reaction is maintained at about 195 C. The solvent employed is diethylene glycol dibutyl ether and the carbon monoxide is maintained at a pressure of p.s.i. Generally similar yields are obtained except that the product is cyclopentadienyl manganese tricarbonyl.

EXAMPLE VI Example I is repeated except that ethyl cyclopentadienyl manganese iodide is reacted with carbon monoxide in tetrahydrofuran solvent in the presence of an equimolar quantity of benzyllithium. The carbonylation reaction is conducted at C. and the carbon monoxide pressure is maintained at about 1000 p.s.i.g. The ethyl cyclopengadienyl manganese tricarbonyl is recovered in good yiel EXAMPLE VII Indenyl manganese acetate is reacted with carbon monoxide in dicyclohexylamine solvent in the presence of 0.1 mole of diethylmagnesium per mole of the indenyl manganese acetate. The reaction conditions are comparable to Example I and the product is indenyl manganese tricarbonyl.

EXAMPLE VIII cyclopentadienyl manganese t-butoxide is reacted in hexane solvent (50 parts) in the presence of n-decylsodium. In this case, the carbon monoxide pressure is 750 p.s.i.g. and the reaction is conducted at C. The cyclopentadienyl manganese tricarbonyl product is obtained in good yield and the product is not contaminated by'appreciable quantities of polymeric material.

Example I is repeated using other solvents, specifically dicyclopentadiene, toluene, diethyl ether, ethylene glycol dimethyl ether, dioxane, morpholine, triethyl glycol dimethyl ether and similar results are obtained.

I claim:

1. Process for producing a cyclopentadienyl manganese tricarbonyl in which the cyclopentadienyl moiety is a cyclopentadienyl hydrocarbon group having from 5 to about 13 carbon atoms comprising reacting a cyclopentadienyl manganese salt in which the cyclopentadienyl moiety is as defined above and in which the anion of said salt is monovalent, with carbon monoxide and from about 0.1 mole to about 2 moles, per mole of said salt, of a reducing agent having the general formula MR wherein M is a metal selected from the group consisting of group I-A, II-A and IIIA of the periodic table, R is a radical selected from the group consisting of hydride, alkyl, alkynyl, alkenyl and aryl and x is an integer equal to the valence of the metal, at a temperature of from about 50 to about 300 C. at a pressure of 1 to 1000 atmospheres.

2,916,505 7 8 2. The process of claim 1 wherein the anion is a halide. 6. The process of claim 1 wherein the cyclopentadienyl 3. The process of claim 1 wherein the reaction is cargroup has 6 carbon atoms.

ried out in an inert solvent.

4. The process of claim 1 wherein the reducing agent References Clted 1n the file of thls Patent is an alkyl aluminum compound. 5 UNITED STATES PATENTS 5. The process of claim 1 wherein the cyclopentadienyl group has 5 carbon atoms 2, 18,417 Brown et al Dec. 31, 1957 

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